(Adapted from the applicant's abstract): ODT combines laser Doppler flowmetry (LDF) with optical coherence tomography to obtain high resolution tomographic images of static and moving constituents in highly scattering biological tissues. Such localization is possible because the detected ODT interference fringe intensity measures the back scattered light at a discreet user-specified location within the test material only for coherent photons that have a time-of-flight difference that matches the reference-target optical delay to within the source coherence length. Furthermore, in contrast to conventional LDF, the overall ODT signal due to moving RBC is entirely due to the Doppler shifted and broadened back scattered light. As a result, signal to noise ratios are substantially higher. Raster scanning the target fiber probe allows construction of a three-dimensional tomography map of the underlying microcirculation. It is a method that can probe blood flow at discrete user-specified locations in highly scattering biological tissues would have decided advantages over existing methodology. The specific aims of this proposal are to: (1) develop an ODT instrument for real-time tomographic imaging of in vivo blood flow in highly scattering biological tissues; (2) verify operation of the ODT instrument to obtain real-time tomographic images of blood flow at discreet user-specified locations using model in vitro and in vivo turbid samples; and (3) develop an image reconstruction procedure to obtain structural and velocity images of static and moving constituents from the measured spectral interference fringe intensity.